1. Field of the Invention
The present invention relates to precipitated silicas with a broad pore size distribution of the pores with a pore diameter smaller than that of the maximum of the derivative of the pore volume distribution function, to a process for their production and to their use.
Precipitated silicas have long been used in elastomer mixtures, an example being tires. U.S. Pat. No. 6,013,234, EP 0647591 and WO 03/016215 provide examples here.
Stringent requirements are placed upon silicas used in tires. The intention is that they can be dispersed easily and effectively in the rubber and can enter into rapid and effective bonding with the respective polymer chains of the rubber used by way of a coupling agent, e.g. bifunctional silanes. Greater effectiveness of this phenomenon during the mixing process leads to better abrasion resistance in the finished tire. Other important properties are described via the specific surface areas (BET or CTAB) and the oil absorption capacity (DBP).
Introduction of silica technology in what are known as “green tires” has permitted a dramatic reduction in rolling resistance, while abrasion performance has remained at approximately the level of a tire filled only with Carbon Black. Constantly rising raw material prices and an awareness of responsibility for the environment have led to increasing importance placed on further improvements in abrasion resistance and rolling resistance of tire mixtures.